(-)-Mandelic acid → (-)-7-Amino-5-benzyl-7-methyl-5-azaspiro[2.4]heptane d-mandelate

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Reaction Steps

Toluene (11.5 L) was added to a solution (1,660 mL) of 7-amino-5-benzyl-7-methyl-5-azaspiro[2.4]heptane (2,202 g, purity: 35%) in toluene, and D-mandelic acid (325.2 g) was added to the mixture, followed by cooling. Seed crystals for the title compound were added to the cooled mixture, followed by stirring overnight at an internal temperature of −10° C. The precipitated crystals were collected through filtration and washed twice with cold toluene, followed by drying under reduced pressure. The thus-obtained crude products (first crude crystals) were suspended under stirring in toluene (2.2 L) at room temperature. After 2.5 hours, the suspension was filtered so as to collect crystals. The collected crystals were washed with cold toluene, followed by drying under reduced pressure, to thereby yield the title product as white crystals (first crystals) (365.4 g, yield: 27.1%, optical purity: 97.4% e.e.).

Provenance & Evidence